1. Field of the Invention
The present invention relates to a processing apparatus of a conveying type having at least two processing baths, which makes it possible to effectively prevent a solution in a processing bath and that in the bath preceding the same from causing admixing with one another.
2. Description of the Prior Art
In a processing apparatus of a conveying type having at least two processing baths, it is generally required that the apparatus is designed so as to reduce the amount of a processing solution carried over, by a processed material or other members of the apparatus such as means for spraying the processed material with a processing solution, from a preceding bath to a subsequent bath or vice versa as low as possible. For that purpose, squeeze rollers are disposed at the outlet of the preceding processing bath to prevent the solution in the preceding bath from being carried over by a processed material therefrom to that in the subsequent bath. Moreover, guide rollers are disposed at the inlet of the subsequent bath to prevent the processing solution in the subsequent bath from being carried over by the rotatable squeeze roller therefrom to the preceding bath.
In particular, when a presensitized plate for use in making lithographic printing plate (hereunder referred to as "PS plate(s)"), which has been imagewise exposed to light, is processed in a conveying type processing apparatus, it is of primary importance to reduce the amount of each processing solution carried over, by the PS plate from a processing bath to other processing baths or vice versa as low as possible.
A lithographic printing plate can generally be prepared by the imagewise exposing to light of a PS plate composed of a substrate provided thereon with a light-sensitive resin layer, developing and at least one processing selected from the group consisting of water washing, rinsing and desensitization.
In such a case, if a large amount of each processing solution is carried over by the processed PS plate which is conveyed through each processing device, for instance, from the developing bath to the water washing or rinsing bath; from the water washing or rinsing bath to the developing bath; from the developing bath to the desensitizing bath; from the desensitizing bath to the developing bath; from the water washing or rinsing bath to the desensitizing bath; and from the desensitizing bath to the water washing or rinsing bath, each processing solution is deteriorated within a very short period of time.
In order to prevent the deterioration of each processing solution due to admixing with other processing solutions which are possibly carried over by the processed PS plate from the preceding baths or by a means for spraying the plate with a processing solution from the next baths, a pair of squeeze rollers are disposed at both upstream and downstream sides of each processing bath. Moreover, a device for spraying the surface of a processed plate with each processing solution, in a spraying type processing apparatus, is placed at the upstream and/or downstream sides of the squeeze rollers as already mentioned above. In such a conventional apparatus for making lithographic printing plates, at least two pairs of rollers are disposed in each processing bath, which, therefore, makes the apparatus very expensive and large-sized, and, thus, the apparatus occupies a greater space.